This invention relates to an improvement applicable to wire electrode type electrical discharge machining equipment. More specifically, this invention relates to an improvement which is applicable to wire electrode type electrical discharge machining equipment and which is developed for the purpose, of decreasing the length of time required for rough machining, without an increase in the floor space and/or in the economical burden.
The major conventional methods for producing a metal mold to be employed for pressing work was a method in which a die sinking machine and a grinder were employed in combination. At present, however, electrical discharge machining, particularly wire electrode type electrical discharge machining, has replaced the foregoing conventional method.
Wire electrode type electrical discharge machining allows a workpiece of a conductor e.g. an extremely hard metal to be machined in a complicated and irregular shape with high accuracy or within the maximum error range of 1 micrometer and with a very high grade of smoothness for the machined surface.
On the other hand, laser machining equipment is available with which an arbitrary workpiece can be machined in a complicated and irregular shape at an extremely high machining rate (approximately 1 m/min). The laser machining has, however, a drawback in which the machining accuracy is unsatisfactory and particularly the smoothness of the machined surface is awkward. This is due to the principle of laser machining which is based on a local melting of the extremely small part of a workpiece, the local melting being caused by exposure of the small part of the workpiece with a laser beam having a small area and a very high energy density.
Wire electrode type electrical discharge machining generally consists of two steps including the first step in which roughing is conducted at a relatively high machining rate and the second step in which finishing is conducted at a relatively low machining rate. In any case, however, wire electrode type electrical discharge machining has a drawback wherein the machining rate is low, resultantly requiring a long time for machining a unit quantity of a workpiece. Even in the case of roughing, the machining rate is approximately 10 mm/min, provided the thickness of the workpiece is approximately 10 mm, despite the corresponding rate of laser machining is approximately 1 m/min.